Creating a 3d paint streak effect in Blender 2.8
Best way would be to create a texture, sculpting it is not the way to go in my opinion. I've actually done similar things in C4D. We would shoot real paint on camera on a white background, get rid of the background in photoshop and just assign it to a plane. Then you can do whatever you want with the plane, twist it and move it around. It's the easiest way and give the best result, you can just change color with a HUE node. Use the image to add displacement as well. An other way would be to create the texture fully procedurally but that's a bigger subject.

Give me 10 minutes I'll update my answer with an example .blend file.

EDIT: